Project I concerns the functional organization of the herpes simplex and Epstein-Barr virus genomes. The objectives of this project are to map and define the viral genes with specific emphasis on genes responsible for transformation of cells and for the maintenance of the transformed state. Project II concerns the expression of HEL 12 retrovirus. The objectives of this project are to characterize the gene product specified by this virus in human tissues by molecular probes and by immunologic approaches.